run_project_tests: fix assertion that crashes if you have git worktrees

git worktrees are frequently a handy tool to use. This glob pattern
asserts an error if the same named directory appears more than once,
which it will -- once per worktree -- but only because it is globbing
the entire project root, even though it should always only exclusively
care about files in `test cases/`. So just glob correctly, and then I
can run the testsuite locally again.

run_project_tests.py

@@ -1550,7 +1550,7 @@ def print_tool_versions() -> None:
         print('{0:<{2}}: {1}'.format(tool.tool, get_version(tool), max_width))
     print()
 
-tmpdir = list(Path('.').glob('**/*install functions and follow symlinks'))
+tmpdir = list(Path('.').glob('test cases/**/*install functions and follow symlinks'))
 assert(len(tmpdir) == 1)
 symlink_test_dir = tmpdir[0]
 symlink_file1 = symlink_test_dir / 'foo/link1'